Zika spread boosts demand for mosquito irradiation technology

Several Latin American countries searching for ways to control Zika-carrying mosquitoes have recently turned to the International Atomic Energy Agency (IAEA) for help, experts of the organization said Tuesday.

Brazil, El Salvador and several other Central American countries have expressed interest in using technology developed by the IAEA to sterilize male mosquitoes by irradiating them to drive down populations of the insect.

"Basically it is family planning for insects," said Jorge Hendrichs, who heads the IAEA's pest control section.

Experts of the IAEA and the UN Food and Agriculture Organization have developed ways to breed millions of these insects and to expose them to a few minutes of radiation, a method that does not make the animals radioactive.

As male insects are released in weekly waves, they mate with females, who then lay eggs that do not hatch.

"If Brazil released a huge number of sterile males it would take a few months to reduce the population," said Aido Malavasi, a Brazilian insect control expert who heads the IAEA's department for applied nuclear science.

However, it is currently only feasible to use the so-called sterile insect technique in middle-sized cities of 150,000 to 200,000 people where the spread of the irradiated mosquitoes can be controlled and monitored, he said.

The irradiation method has successfully been used for some time to control fruit flies that damage crops, tsetse flies, screwworm flies and other insects. Rearing mosquitoes for this purpose only started ten years ago.

While using sterile insect technique on mosquitoes was still in the "early days," it worked, Hendrichs said, comparing the stage of development to early car models.

"We have a car that is driving, in a very simple way," he said, adding that countries that acquire the know-how from the IAEA for free would then have to implement it in the field.

In a field trial in Italy, a mosquito population dropped 80 per cent over nine months, while the success rate in a Chinese trial was close to 100 per cent, according to the IAEA.

"The technology is there, but it is up to countries to decide how fast they want to go," Hendrichs said.

In any case, the IAEA officials stressed that their technology was only one possible method that would have to be complemented by other measures, such as reducing wet breeding mosquito grounds in populated areas.

Scientists have also been looking at other ways to control pests.

British company Oxitec has been successfully testing genetically modified male mosquitoes to reduce the numbers of insects.

The IAEA's method was safer because countries or communities could choose to stop releasing male mosquitoes, Hendrichs said, adding, that with genetic engineering, "you don't know what unforeseen consequences there may be."

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